molecular simulation of carbon dioxide, brine, and … simulation of carbon dioxide, brine, and clay...

Molecular Simulation of Carbon Dioxide,

Brine, and Clay Mineral Interactions

Craig M. Tenney and Randall T. Cygan

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation,

a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s

National Nuclear Security Administration under contract DE-AC04-94AL85000.

SAND 2013-6721P

103 m 103 m

Carbon capture and geological storage

Big Picture

Time

104 years

1. Capture CO2

2. Inject it deep underground

3. Hope it stays there

injection well abandoned well fault

caprock storage zone

caprock jointing

1 km Scale:

Slide from: CFSES EFRC Science Review;

Denver, CO; January 2012; Joe Bishop (SNL)

Field-scale modeling

log Time (s)

-15 -12 -9 -6 -3 0 3 6 9 12 15

log D

ista

nce (m

)

-9

-6

-3

0

3

6

Finite

Element

Analysis

Continuum

Methods and

Mesoscale

Modeling

Molecular

Mechanics

Quantum

Mechanics Å

mm

m

mm

km

min year day Ma ms ms ns

ps fs

e

atoms

nm

blobs

s ka

bulk

Multiscale simulation

Geological carbon storage

Up Close

reservoir rock cap rock

Source: Cooperative Research Centre

for Greenhouse Gas Technologies,

http://www.co2crc.com.au/

Source: Hongkyu Yoon (SNL)

Sub-pore scale

• interfacial tension g12

– surface free energy

• contact angle θC – indication of wettability

C12S2S1 cosggg Source: Kuldeep Chaudhary (UT Austin)

Pore- and field-scale

• capillary pressure pc

– overpressure required to

displace current fluid with

new fluid

• relative permeability

– fractional permeability of

a fluid in the presence of

other fluid(s)

rpc

C12 cos2 g

liquid CO2

Water (10% NaBr)

10-3 m

Source: Kuldeep Chaudhary (UT Austin)

Molecular simulation of aqueous and

supercritical CO2 nanodroplets

H

Al

Si

O siloxane surface

(hydrophobic)

gibbsite surface (hydrophilic)

kaolinite

Simulation details

• (20 x 20 x 17) nm

•3 kaolinite layers

(bottom two fixed)

•330K, 20MPa

•10-15 ns

•CO2 in H2O

– 600k atoms

•H2O in CO2

– 300k atoms

•brine systems

– 0.7 M NaCl

– 0.2 M CaCl2

siloxane (hydrophobic) surface

0.7M NaCl in CO2 – initial configuration

front view oblique view


0.7M NaCl in CO2 – final configuration




carbon dioxide water



water Na+ Cl−

gibbsite (hydrophilic) surface

CO2 in H2O – initial configuration



CO2 in H2O – final configuration


CO2 in 0.7M NaCl – final configuration



water Na+ Cl−


CO2 in 0.2M CaCl2 – final configuration



water Ca2+ Cl−

Summary

• Simulation shows realistic behavior for CO2, H2O,

and ions on hydrophilic and hydrophobic basal

surfaces of kaolinite.

• Possible future application: rational design of

surfactants, coatings, enhanced oil or gas

recovery

Acknowledgments

• Simulation development aided by discussions with

– Louise Criscenti (SNL)

– Ian Bourg (LBNL)

• This research is funded by the Center for Frontiers

of Subsurface Energy Security (CFSES), a U.S.

Department of Energy Office of Basic Energy

Sciences Energy Frontier Research Center, under

Contract No. DE-SC0001114.

supplementary slides


CO2 in H2O

initial final



top view front view

siloxane surface – H2O in CO2

siloxane surface – 0.2M CaCl2 in CO2

water Ca2+ Cl−


water Ca2+ Cl−

CO2 and H2O in mica slit pores

initial configuration


final configurations


CO2 density


H2O density


K+ density

Summary

• kaolinite hydrophilic surface

– layers of water (and ions) completely displace CO2

• kaolinite hydrophobic surface

– strong CO2 wetting in presence of water and brine

– weak water and brine wetting in presence of CO2

• mica slit pores

– unconfined CO2 is completely displaced by well-

developed water layers

– strongly confined CO2 displaces diffuse water

layers, slightly altering contact angle

molecular simulation of carbon dioxide, brine, and … simulation of carbon dioxide, brine, and clay...

Documents